There is no effective therapy for hormone refractory prostate cancer. Several characteristics of monoclonal antibodies (mAbs) are particularly well suited for the demands of prostate cancer therapy. mAb Prost 30 binds specifically with a prostate related antigen. The investigators wish to define the toxicity and preliminary efficacy of 131 Iodine-mAb Prost 30 in patients with hormone refractory prostate cancer. Progress report and summary of findings: No additional patients were enrolled during this period. Patients previously entered into this protocol were followed for a minimum of 8 weeks following Prost 30 administration, or, if their disease stabilized or responded, until progression. While an initial decline in serum PSA was seen in 2 of the 7 patients treated, ultimately all seven patients experienced a progression of their disease.